(Reuters) – A 36-year-old woman was accused of causing $10,000 worth of damage to a painting by the late abstract expressionist artist Clyfford Still, a work valued at more than $30 million, authorities said on Wednesday.

A police report said Carmen Tisch punched and scratched the painting, an oil-on-canvas called “1957-J no.2″, at the recently opened Clyfford Still museum in Denver and pulled her pants down to slide her buttocks against it.

Tisch was charged with felony criminal mischief on Wednesday and has been held on a $20,000 bond since the incident in late December, said Lynn Kimbrough, spokeswoman for the Denver District Attorney’s Office.

Kimbrough said Tisch urinated after she rubbed up against the canvas, but whether urine got on the painting was still under investigation, she said.

Born in North Dakota in 1904, Still was considered one of the most influential of the American post-World War Two abstract expressionist artists, although he was not as well known as others such as Jackson Pollock.

Still died in 1980, and the city of Denver worked for years with his widow, Patricia, to secure the single-artist museum. She died in 2005, and her husband’s collection was bequeathed to the city.

Four of Still’s works were auctioned by Sotheby’s last year for $114 million to endow the Denver museum, which opened with much fanfare in November.

Because Still closely guarded his works, most of the pieces at his namesake museum had not previously been displayed.

Tisch will be formally advised of the charges on Friday, Kimbrough said.